Current practice for completing downhole structures, particularly deepwater wells, involves stimulating, hydraulic fracturing, frac packing and/or gravel packing one or more zones and then landing a fluid isolation valve, typically a ball valve system, above the treated zones. The fluid isolation valve temporarily blocks fluid flow so that an upper completion string can be run and connect the treated zones to surface for enabling production after the fluid isolation valve is opened. Although such systems do generally work for their intended purposes, they are not without limitations. For example, these known ball-type fluid isolation valves do not provide an efficient and reliable system for periodically replacing portions of the upper completion, and may require wireline intervention, hydraulic pressuring, or the running and/or manipulation of a designated tool to control the fluid isolation valve. For example, artificial lift systems (e.g., electric submersible pumping systems or ESPs), are increasingly desirable, particularly for use in deepwater wells. Accordingly, advances in downhole valve technology, at times referred to as “mechanical barriers”, particularly for deepwater wells and/or for enabling more reliable and efficient replacement of upper completion systems and components, are always well received by the industry.